The invention relates to a telescopic sight with variable magnification, comprising a fixed objective and first image plane assigned thereto, a variable system with second image plane assigned thereto, and a fixed eyepiece for viewing the second image plane.
Such telescopic sights are known from the prior art and are required for viewing and aiming at remote objects. It is necessary in this case to make an erect and laterally correct image available to the observer. In the case of sights with variable magnification, it is possible in conjunction with low magnification for the user to survey a large field of view that can be used to find an object easily. For the purposes of accurate aiming, the object found is observed more accurately with the aid of a large magnification, although then with a restrictive field of view. Reflections owing to tube walls or other glossy or shining parts of the telescopic sight are reduced in a known way by fitting light traps, matt construction black surfaces or stops. It is the case, in particular, in telescopic sights that the construction space is limited by mechanical stipulations, for example the fastening devices on the firearm. Consequently, stops can frequently not be fitted. For this reason, the mounts of the lenses are simultaneously used in part as stops that also have the task, inter alia, of sharply delimiting edge regions of the imaging lenses, which would yield an unsharp image, and of impeding production of images.
U.S. Pat. No. 4,255,013 discloses a telescopic sight in the case of which an inversion system can be shifted along the optical axis via an adjusting ring arranged on the eyepiece side.
U.S. Pat. No. 3,782,822 discloses a telescopic sight of the type mentioned at the beginning that has an objective and an eyepiece. The inversion system is designed as a zoom system and enables a variable magnification of the telescopic sight. An optical target is located in a rear image plane between the inversion system and eyepiece.
U.S. Pat. No. 4,172,634 discloses a lens inversion system for a telescopic sight, the said system being designed as a two-element zoom system and its adjusting elements being supported in an inner tube such that they can be displaced along the optical axis. The adjusting elements slide along the inside of the inner tube when the magnification is varied. This inside must be of smooth design for acceptable functioning, and therefore produces undesired light reflections. These disturbances, also denoted as false light or veiling glare, occur particularly when magnification is set high. Light that is incident in the objective of the telescopic sight laterally from ahead from outside the field of view is reflected on parts of the mount, for example in the lens inversion system, and passes into the eye of the observer through the eyepiece as disturbing false light. Owing to the limited conditions of construction space in the diameter of the telescopic sight, it is impossible to suppress this false light with conventional methods such as, for example, stops or light traps on the parts of the mount. As a makeshift, reflecting surfaces are anodized or painted to be black, but these measures lead at best to a reduction in the intensity of the false light. In the region of moving components, smooth and therefore necessarily reflecting, surfaces must remain, since these surfaces cannot be permanently provided with a light-absorbing layer owing to the friction generated during movement.
If, when magnification is set high, the observer does not keep the ideal distance from the eyepiece, his eye thus not being located in the so-called exit pupil position, said observer perceives a dark edge around the then reduced field of view in which disturbing reflections become visible. As soon as the eye is removed only a little from the optical axis, or the observer attempts to detect an object at the edge of the field of view, a round scattered light phenomenon occurs and clearly outshines the wide dark edge.